1. Field of the Invention
The present invention relates generally to an engine idling correction system for an automotive vehicle having an air conditioner and an automatic transmission, and more particularly to an actuator provided for the system, in which two vacuum compartments are arranged so as to open the throttle valve; that is, so as to increase the engine revolution speed under engine idling conditions, independently or simultaneously, whenever a thermostat or a neutral switch is turned on.
2. Description of the Prior Art
Generally, if an air conditioner is turned on while the engine is idling, the engine speed is lowered. This is because an increase in engine load due to a compressor provided for the air conditioner will lower the engine speed under engine idling conditions. Therefore, it is necessary to correct, or raise, the engine speed.
In addition, in the case of an automotive vehicle provided with an automatic transmission, there are many cases where the vehicle is left parked with the shift lever set to L(Low) or D(Drive) position. In this case, since an increase in engine load due to the automatic transmission will further lower the engine speed, if both the load due to the air conditioner and the automatic transmission are applied to the engine at the same time, a conventional engine idling correction system for correcting only a drop in engine speed due to the air conditioner cannot control the lowering of the engine speed. As a result, the engine may cause vibration or deterioration in cooling performance within the passenger compartment, and thereby the passengers may feel discomfort.
To cope with this problem, two separate actuators or a two-stage operation-type actuator has generally been used for correcting a decrease in engine speed caused by both the loads of the air conditioner and the automatic transmission.
However, in the case of the two-stage operation type actuator, since this actuator is required to determine the priority order of operation start and end, it is necessary to provide an additional control unit for controlling an vacuum circuit to activate the actuator in order. On the other hand, in the case of two separate actuators, the system is more complicated.
In any case, since such a system is inevitably costly, there has been a need for a more simple, less costly actuator mounted in an automotive vehicle having an automatic transmission and an air conditioner.